1. Field of the Invention
The present invention relates to a wireless Local Area Network (LAN) base station device and a communication method therefor and particularly, to a wireless LAN base station device having plural antennas for making communications with wireless terminals and plural transmission-reception portions connected to the plural antennas, and a communication method therefor.
2. Description of the Related Art
JP-A-11-239091 (hereinafter referred to as “patent document 1”) discloses an example of the construction of a wireless base station device in which an antenna unit for expanding a wireless-communication possible area of a wireless base station is arranged in the neighborhood of the wireless-communication possible area of the wireless base station or out of the wireless-communication possible area by connecting to the wireless base station through an RF signal coaxial cable when it is difficult to make wireless communications with the wireless base station although the distance to the wireless base station is actually near in the Personal Handyphone System (PHS) system.
Furthermore, JP-A-11-341540 discloses that in a cellular phone system a cell is divided into plural sectors, each sector is covered by using at least three antennas while parts of the coverage areas of two antennas of these three antennas are overlapped with each other and an antenna which provides the maximum level to a reception signal from a mobile is selected as a main antenna on the basis of an instruction of the mobile.
However, the wireless base station device and cellular phone system described above are inadequate for enabling a wireless terminal to move with no interruption of communication, energy saving, etc.